A crannog is a man-made island dwelling, typically constructed from timber, peat, and brushwood piled into shallow water, and used as a defended homestead at various points from the Neolithic period right through to the seventeenth century in Ireland. Their appeal was practical: surrounded by water, they were difficult to attack and easy to defend, and the lake itself provided food and transport.

The Derryronan example sits within a landscape that would have supported this kind of settlement for much of Irish prehistory and the early medieval period. Mayo's midlands and western lake districts are scattered with such sites, many of them unexcavated and known only from their surface form, a roughly circular mound of vegetation-covered spoil rising just above the waterline. Without further investigation it is rarely possible to say with confidence when a particular crannog was built, who occupied it, or how long it remained in use. What can be said is that crannogs in this region often served as the residences of local lords and their households, places where valuables were stored and authority was exercised over the surrounding territory.